CN102812169A - Cationic microfibrillated plant fiber and its production method - Google Patents

Abstract

Disclosed is a cationised novel microfibrillated plant fibre and a manufacturing method for the same. The cationised microfibrillated plant fibre is cationised using a compound containing a quaternary ammonium group, and the average fibre diameter is 4 - 200nm.

Description

Cationic microfibrillated plant fiber and its production method

technical field

The present invention relates to cationic microfibrillated plant fibers and a method for their production.

Background technique

Various methods are known for microfibrillating plant fibers (for example, wood pulp, etc.) to obtain microfibrillated plant fibers (nanofibers) in which the fiber diameter is reduced to nanometer order. For example, Patent Document 1 discloses that cellulose fibers having a specific fiber length are microfibrillated to obtain microfibrous cellulose having a small fiber diameter, a long fiber length, and excellent water retention properties, etc. . In addition, Patent Document 2 proposes a method of weakening the adhesive force of unnecessary lignin, hemicellulose, etc. contained in cellulose-based fiber materials by retorting the fiber materials, Promotes nanofibrillation. In addition, as a method of promoting nanofibrillation and directly producing cellulose nanofibers from lignocellulose, the following method has also been proposed. Cellulose is processed (Patent Document 3).

On the other hand, a method of adding a hydrophobizing chemical such as an anionic, cationic, or nonionic surfactant to cellulose-based fibers and then performing a mechanical stirring treatment to impart high voids to the cellulose-based fibers has been disclosed. , to increase the water absorption of fibers used in paper diapers and the like (Patent Document 4). In addition, although it is not aimed at the production of microfibers such as microfibrillated plant fibers (nanofibers), similarly to Patent Document 4, it has also been proposed to introduce cationic groups into the surface of cellulose-based fibers, Cationic charge is made on the fiber surface to increase affinity with anionic dyes, or it is further miniaturized to improve water retention, shape retention, and dispersibility while maintaining the function as cellulose particles (Patent Document 5).

prior art documents

patent documents

[Patent Document 1] Japanese Unexamined Patent Publication No. 2007-231438

[Patent Document 2] Japanese Unexamined Patent Publication No. 2008-75214

[Patent Document 3] Japanese Patent Laid-Open No. 2008-308802

[Patent Document 4] Japanese Patent Application Laid-Open No. 8-10284

[Patent Document 5] Japanese Unexamined Patent Publication No. 2002-226501

Contents of the invention

The problem to be solved by the invention

The main object of the present invention is to provide novel cationized microfibrillated plant fibers and a method for producing the same.

means of solving problems

As mentioned above, when producing microfibrillated plant fibers from plant fibers such as wood pulp, it is known that nanofibrillation is promoted by improving the starting material or defibrillation method, or that water retention is improved by chemically treating the raw material fibers. sex. However, in the case of highly micronized fibers such as microfibrillated plant fibers, the dispersion of the fibers and the degree of damage to the surface are different depending on the method of defibrillation or chemical treatment, and they have a great impact on the formation of microfibrils. Physical properties such as strength and the like when chemically plant fiber sheets or resin composites vary greatly. The inventors of the present invention have conducted intensive studies on a production method that can easily obtain microfibrillated plant fibers from a plant fiber-containing material and is excellent in the strength of the obtained microfibrillated plant fibers. As a result, it was found that the cellulose fiber-containing material is cationically modified by (1) reacting the hydroxyl group in the cellulose fiber-containing material with a cationizing agent having a quaternary ammonium group, and (2) the obtained The production method of the cationically modified fiber in the presence of water is not only easy to defibrate the plant fiber, but also can obtain a particularly excellent strength when it is made into a sheet or a composite with a resin. Microfibrillated plant fibers.

Microfibrillated plant fibers are usually anionically charged, although in a small amount, due to reasons such as partial oxidation of the reducing end. Therefore, even if the plant fibers are only cationic-modified, the bond formation between fibers is promoted due to electrostatic interaction, and the strength may be improved. However, since the anionic group contained in the plant fiber is extremely small, its effect is small. However, as a result of intensive studies by the present inventors, it has been found that microfibrillation remarkably proceeds by applying mechanical shear stress after cationic modification of plant fibers.

The present invention is based on such findings and has been completed after repeated intensive studies. That is, the present invention provides microfibrillated plant fibers described in the following items 1 to 7, a method for producing the same, a sheet comprising the plant fibers, and a thermosetting resin composite comprising the plant fibers.

Claim 1. A cationic microfibrillated plant fiber, which is a cationic microfibrillated plant fiber having an average fiber diameter of 4 to 200 nm after cationic modification with a quaternary ammonium group-containing compound.

Item 2. A cationic microfibrillated plant fiber having a degree of substitution of quaternary ammonium groups per anhydroglucose unit of 0.03 to less than 0.4, and an average fiber diameter of 4 to 200 nm.

Item 3. The method for producing cationic microfibrillated plant fibers according to Item 1 or 2, comprising the following steps (1) and (2):

(1) A step of cationically modifying the cellulose fiber-containing material by reacting hydroxyl groups in the cellulose fiber-containing material with a cationizing agent having a quaternary ammonium group; and

(2) A step of defibrating the obtained cationically modified fibers in the presence of water until the average fiber diameter is 4 to 200 nm.

Item 4. A sheet comprising the cationic microfibrillated plant fiber according to Item 1 or 2.

Item 5. A thermosetting resin composite comprising the cationic microfibrillated plant fiber according to Item 1 or 2.

Item 6. The thermosetting resin composite according to Item 5, wherein the thermosetting resin is an unsaturated polyester resin or a phenolic resin.

Item 7. A method for producing a thermosetting resin composite, comprising the step of mixing the cationic microfibrillated plant fiber according to Item 1 or 2 and a thermosetting resin.

The effect of the invention

The present invention adopts (1) the process of cationically modifying the material containing cellulose fiber by reacting the hydroxyl group in the material containing cellulose fiber with a cationizing agent having a quaternary ammonium group, (2) modifying the obtained cation The production method of the step of defibrating the natural fiber in the presence of water can play the following effects, that is, it is easy to carry out the defibrating treatment of the raw material, and when the obtained microfibrillated plant fiber is made into a sheet or resin The composite is particularly excellent in terms of strength. In addition, the average value of the fiber diameter of the microfibrillated plant fiber of the present invention is as small as about 4 to 200 nm, and is extremely excellent in terms of strength. Thus, the present invention can be used in the inner packaging materials, outer packaging materials, and structural materials of transportation machines; the frames, structural materials, and internal components of electrified products; the frames, structural materials, and internal components of mobile communication machines, etc.; It is used in a wide range of fields such as housings, structural materials, internal parts, etc. of music reproduction machines, image reproduction machines, printing machines, copiers, sporting goods, etc.; building materials; office equipment such as stationery.

Description of drawings

FIG. 1 is an electron micrograph (10,000 times) of cationic microfibrillated plant fibers obtained in Example 3. FIG.

FIG. 2 is an electron micrograph (20,000 times) of cationic microfibrillated plant fibers obtained in Example 3. FIG.

FIG. 3 is an electron micrograph (50000 times) of cationic microfibrillated plant fibers obtained in Example 4. FIG.

FIG. 4 is an electron micrograph (10000 times) of the cationic plant fiber obtained in Comparative Example 1. FIG.

FIG. 5 is an electron micrograph (250 times) of cationic plant fibers obtained in Comparative Example 3. FIG.

Detailed ways

Next, the cationic microfibrillated plant fiber of the present invention, its production method, a sheet obtained from the plant fiber, and a thermosetting resin composite will be described in detail.

The cationic microfibrillated plant fiber of the present invention is characterized in that the average value of the fiber diameter is as small as about 4 to 200 nm, and the microfibrillated plant fiber is cationically modified with a compound having a quaternary ammonium group.

In the cell wall of a plant, cellulose microfibrils (single cellulose nanofibers) with a width of about 4 nm exist as the smallest unit. It is the basic skeletal substance (basic element) of plants. In addition, the cellulose microfibrils aggregate to form the skeleton of the plant. In the present invention, the so-called microfibrillated plant fiber is a material containing plant fibers (for example, wood pulp, etc.) unraveled so that the fibers thereof are nano-sized.

The average value of the fiber diameter of the cationic microfibrillated plant fibers of the present invention is usually about 4 to 200 nm, preferably about 4 to 150 nm, particularly preferably about 4 to 100 nm. In addition, the average value of the fiber diameters of the cationic microfibrillated plant fibers of the present invention is an average value when at least 50 or more cationic microfibrillated plant fibers are measured within the field of view of an electron microscope.

The microfibrillated plant fiber of the present invention can be produced, for example, by a method including the following steps (1) and (2).

Step (1): a step of reacting a hydroxyl group in a material containing cellulose fibers with a cationizing agent having a quaternary ammonium group to cationically modify the material containing cellulose fibers, and

Step (2): A step of defibrating the obtained cationically modified fiber in the presence of water until the average value of the fiber diameter is about 4 to 200 nm.

In step (1), examples of the cellulose fiber-containing material (cellulose fiber-containing material) used as a raw material include wood, bamboo, hemp, jute, kenaf, cotton, sugar beets, agricultural product residues, Pulp obtained from natural cellulose raw materials for cloth, mercerized cellulose fibers, regenerated cellulose fibers such as rayon or celluloid, etc. In particular, pulp can be mentioned as a preferable raw material.

As the pulp, chemical pulp (kraft pulp (KP), sulfite pulp (SP)), semichemical pulp obtained by pulping plant raw materials chemically, mechanically, or both, can be used. pulp (SCP), chemical groundwood pulp (CGP), chemical mechanical pulp (CMP), groundwood pulp (GP), refiner mechanical pulp (RMP), thermomechanical pulp (TMP), chemothermomechanical pulp (CTMP) ), and deinked waste paper pulp, corrugated paper pulp, and magazine waste paper pulp containing these plant fibers as main components are listed as preferred pulps. These raw materials can be delignified or bleached as needed to adjust the amount of lignin in the plant fibers.

Among these pulps, various kraft pulps derived from coniferous trees with high fiber strength (coniferous unbleached kraft pulp (hereinafter sometimes referred to as NUKP), conifer oxygenated unbleached kraft pulp (hereinafter sometimes referred to as NOKP), coniferous Bleached kraft pulp (hereinafter sometimes referred to as NBKP)).

The lignin content in the cellulose-containing fiber material used as a raw material is usually about 0 to 40% by weight, preferably about 0 to 10% by weight. The measurement of the lignin content is a value measured by the Klason method.

The cationic modification reaction in the step (1) (the reaction between the hydroxyl group in the cellulose fiber-containing material and the cationizing agent having a quaternary ammonium group) can be performed by a known method. The material containing cellulose fibers is formed by combining a plurality of anhydroglucose units, and each anhydroglucose unit has a plurality of hydroxyl groups. For example, when a glycidyltrialkylammonium halide is used in the cationizing agent, it is carried out by allowing the cationizing agent and an alkali metal hydroxide as a catalyst to act on the cellulose fiber-containing material used as the raw material.

The cationizing agent having a quaternary ammonium group which acts (reacts) with the cellulose-containing fiber material is a compound having a group reactive with a hydroxyl group of the cellulose-containing fiber material and a quaternary ammonium group. The group reactive with the hydroxyl group of the cellulose-containing fiber material is not particularly limited as long as it reacts with the hydroxyl group to form a covalent bond. For example, an epoxy group or a halohydrin group which can form it, an active halogen group, an active vinyl group, a methylol group, etc. are mentioned. Among them, an epoxy group or a halohydrin group capable of forming it is preferable from the viewpoint of reactivity. In addition, the quaternary ammonium group has a structure of -N ⁺ (R) ₃ (where R in the formula is an alkyl group, an aryl group, or a heterocyclic group which may have a substituent). There are many known materials for such a cationizing agent, and a known cationizing agent can also be used in the present invention.

In this invention, the molecular weight of the cationization agent which has a quaternary ammonium group is about 150-10000 normally, Preferably it is about 150-5000, More preferably, it is about 150-1000. When the molecular weight of the cationizing agent is 1000 or less, it is preferable since the defibration of the material containing cellulose fibers will be easily performed. This is considered to be because the cationization agent permeates into the inside of the cellulose, until the inside of the material containing the cellulose fibers is fully cationized, and the electrical repulsion effect between the cations becomes large, so it is easy to perform fiber defibration. .

Specific examples of the cationizing agent having a quaternary ammonium group that can be used in the present invention include glycidyl trimethyl ammonium chloride, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride and other glycidyl groups. Trialkylammonium halide or its haloalcohol type, etc.

The reaction between the cellulose-containing fiber material and the cationizing agent having a quaternary ammonium group is preferably performed in the presence of an alkali metal hydroxide, water, and/or an alcohol having 1 to 4 carbon atoms. Sodium hydroxide, potassium hydroxide, etc. can be used as an alkali metal hydroxide used as a catalyst. In addition, as water, tap water, purified water, ion-exchanged water, pure water, industrial water, etc. may be used. Moreover, specific examples of alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like. Water and the alcohol having 1 to 4 carbon atoms may be used alone or in combination. When water is used in combination with an alcohol having 1 to 4 carbon atoms, the composition ratio can be appropriately adjusted, but it is preferable to make the quaternary ammonium group of each anhydroglucose unit of the obtained cationic microfibrillated plant fiber The degree of substitution is adjusted so that it is 0.03 or more and less than 0.4.

In the step (1), the ratio of the cellulose fiber-containing material to the cationizing agent is 100 parts by weight of the cellulose fiber-containing material, usually about 10 to 1000 parts by weight, preferably 10 to 800 parts by weight. About 10 to 500 parts by weight of the above-mentioned cationizing agent may be used in an amount of about parts by weight.

In addition, the proportion of the alkali metal hydroxide used is usually about 1 to 7 parts by weight, preferably about 1 to 5 parts by weight, more preferably about 1 to 3 parts by weight, based on 100 parts by weight of the cellulose-containing fiber material. Servings or so. In addition, the proportion of water and/or alcohol having 1 to 4 carbon atoms is usually about 100 to 50,000 parts by weight, preferably about 100 to 10,000 parts by weight, and more preferably 100 parts by weight of the material containing cellulose fibers. It is preferably about 100 to 500 parts by weight.

In the step (1), the temperature at which the cellulose fiber-containing material acts (reacts) with the cationizing agent is usually about 10 to 90°C, preferably about 30 to 90°C, more preferably about 50 to 80°C . The time for allowing the cellulose fiber-containing material to act (react) with the cationizing agent is usually about 10 minutes to 10 hours, preferably about 30 minutes to 5 hours, and more preferably about 1 to 3 hours. Furthermore, there is no particular limitation on the pressure under which the step (1) is performed, as long as it is performed under atmospheric pressure.

In addition, the cation-modified cellulose-containing fiber material obtained in the step (1) may be provided to the step (2) as it is, but it is preferable to carry out the cation modification in the step (1) and then Components such as the alkali metal hydroxide salt remaining in the reaction system are neutralized with an inorganic acid, an organic acid, etc., and then supplied to the step (2). In addition, in addition to this neutralization step, washing and purification may also be performed by ordinary methods. In addition, the amount of water may be increased or decreased so as to achieve an appropriate fiber concentration in the defibrating treatment in the next step (2).

However, in the present invention, a drying step of the cationically modified cellulose fiber-containing material should not be provided between the step (1) and the step (2). If the cellulose-containing fiber material that has undergone cationic modification in step (1) is dried, even if the dried product is subjected to defibration treatment in the next step (2), it is difficult to obtain the defibrated material as in the present invention. Such nano-sized, high-strength microfibrillated plant fibers. Since the cellulose molecule has many hydroxyl groups, once the drying process has passed, the adjacent fibers of the cellulose-containing fiber material will be connected to each other due to strong hydrogen bonds, and they will be strongly cohesive (such as paper, pulp, etc.) In other words, this kind of aggregation of fibers during drying is called Hornification). It is very difficult to use mechanical force to untie the fibers that have undergone primary coagulation. For example, in Patent Document 5, hornification occurs due to a drying step after the cationization treatment. In this way, no matter how it is mechanically pulverized, only micron-sized particles can be formed.

Thus, in the present invention, the cellulose-containing fiber material subjected to cation modification in step (1) is defibrated in the presence of water in step (2). Known methods can be used for the defibration treatment of cellulose-containing fiber materials. For example, the aqueous suspension and slurry of the cellulose-containing fiber materials can be processed by using a refiner, a high-pressure homogenizer, a grinder, a single A method of mechanically pulverizing or beating with a shaft or multi-shaft mixer or the like to defibrate. If necessary, it is preferable to combine the above-mentioned defibrating methods so as to perform single-screw or multi-screw kneader treatment after refiner treatment.

In the step (2), it is preferable to defibrate the cellulose-containing fiber material subjected to cation modification in the step (1) with a single-screw or multi-screw kneader (hereinafter sometimes simply referred to as "kneader"). The kneader (kneading extruder) includes a single-screw kneader and a multi-screw kneader with two or more shafts, and any of them may be used in the present invention. When using a multi-shaft kneader, since the dispersibility of the microfibrillated plant fiber can be further improved, it is preferable. Among multi-screw kneaders, a twin-screw kneader is preferable from the viewpoint of availability and the like.

The lower limit of the linear velocity of the screw of the uniaxial or multiaxial kneader is usually about 45 m/min.

The lower limit of the linear velocity of the screw is preferably about 60 m/min, particularly preferably about 90 m/min. In addition, the upper limit of the linear velocity of the screw is usually about 200 m/min. The upper limit of the linear speed of the screw is preferably about 150 m/min, particularly preferably about 100 m/min.

L/D (the ratio of the screw diameter D to the length L of the kneading section) of the kneader used in the present invention is usually about 15 to 60, preferably about 30 to 60.

The defibrating time of a single-shaft or multi-shaft kneader varies depending on the type of cellulose-containing fiber material, the L/D of the kneader, etc., but if it is within the range of the aforementioned L/D, it is usually 30 ~ ~ 60 minutes, preferably ~ 30 ~ 45 minutes.

The number of times (rounds) provided to the kneader-based defibration varies depending on the desired fiber diameter, fiber length, and L/D of the kneader, etc. of the microfibrillated plant fibers, but is usually 1 ~8 times, preferably about 1 to 4 times. If the pulp is supplied to the kneading machine for too many times (rounds) of defibration, the defibration proceeds further, but at the same time heat is generated, which may cause cellulose to be colored or thermally damaged. (reduction in sheet strength).

In the kneader, the kneading section where the screw exists may be one, or two or more.

In addition, when there are two or more kneading sections, one or more gate structures (backstops) may be provided between each kneading section. Furthermore, in the present invention, since the linear velocity of the screw is 45 m/min or more, which is considerably higher than that of conventional screws, it is more preferable not to have a gate structure in order to reduce the load on the kneader.

The rotation directions of the two screws constituting the twin-screw kneader may be different or the same. In addition, the meshing of the two screws constituting the twin-screw kneader includes complete meshing, incomplete meshing, and non-sealing, but the meshing used in the defibration of the present invention is preferably the perfect meshing type.

The ratio of the screw length to the screw diameter (screw length/screw diameter) may be about 20 to 150. As a specific twin-shaft kneader, "KZW" manufactured by Technovel, "TEX" manufactured by Nippon Steel Works, "TEM" manufactured by Toshiba Machine Co., Ltd., "ZSK" manufactured by Coperion Corporation, etc. can be used.

The ratio of the raw material pulp in the mixture of the raw material pulp and water used for defibration is usually about 10 to 70% by weight, preferably about 20 to 50% by weight.

In addition, the temperature at the time of kneading is not particularly limited, but usually it can be carried out at 10 to 160°C, and a particularly preferable temperature is 20 to 140°C.

As described above, in the present invention, the cationized plant fiber-containing material may be supplied to predefibration by a refiner or the like before being supplied to defibration in step (2). As a method of predefibrating by a refiner or the like, conventionally known methods can be used. By performing predefibration by a refiner, the load applied to the kneader can be reduced, which is preferable from the viewpoint of production efficiency.

The cationic microfibrillated plant fiber of the present invention can be obtained by the production method as described above, the degree of substitution of the quaternary ammonium group per anhydroglucose unit is 0.03 to less than 0.4, and the degree of crystallinity of the cellulose type I is usually 60 %above. The lower limit of the degree of substitution of the quaternary ammonium group per anhydroglucose unit is preferably about 0.03, more preferably about 0.05. In addition, the upper limit of the degree of substitution is preferably about 0.3, and more preferably about 0.2. Moreover, the degree of substitution varies with the method of defibration treatment. In order to achieve the range of the degree of substitution, the above-mentioned defibration method can be used, and the method of using a mixer, especially a twin-shaft mixer, becomes the range It is particularly preferable in consideration of the above-mentioned numerical range of the desired degree of substitution. In addition, the degree of substitution of quaternary ammonium groups (cation groups) is a value measured by the method described in Examples.

The lignin content in the cationic microfibrillated plant fiber of the present invention is the same as that of the raw material cellulose-containing fiber material, and is usually about 0 to 40% by weight, preferably about 0 to 10% by weight. The measurement of the lignin content is a value measured by the Klason method.

In addition, in the present invention, in order to obtain microfibrillated plant fibers having high strength and high elastic modulus, the cellulose constituting the microfibrillated plant fibers preferably has the highest strength and highest elastic modulus. Type I crystal structure.

The cationic microfibrillated plant fiber of the present invention can be formed into a sheet-shaped molded article. The forming method is not particularly limited, however, for example, the mixed solution (slurry) of microfibrillated plant fibers and water obtained by the above steps (1) and (2) can be filtered by suction, The sheet-like microfibrillated plant fibers are dried, heated and compressed, and the microfibrillated plant fibers are formed into a sheet.

When the cationic microfibrillated plant fiber is formed into a sheet, the concentration of the microfibrillated plant fiber in the slurry is not particularly limited. Usually, it is about 0.1 to 2.0% by weight, preferably about 0.2 to 0.5% by weight.

In addition, the degree of reduced pressure of the suction filtration is usually about 10 to 60 kPa, preferably about 10 to 30 kPa. The temperature during suction filtration is usually about 10°C to 40°C, preferably about 20°C to 25°C.

As a filter, a screen cloth, filter paper, etc. can be used.

By the aforementioned suction filtration, a dehydrated sheet (wet web) of cationic microfibrillated plant fibers can be obtained. Thereafter, if necessary, the obtained dehydrated sheet is immersed in a solvent bath, and then heated and compressed to obtain a dried sheet of microfibrillated plant fibers.

The heating temperature at the time of heat compression is about 50-150 degreeC normally, Preferably it is about 90-120 degreeC. In addition, the pressure is usually about 0.0001 to 0.05 MPa, preferably about 0.001 to 0.01 MPa. The heating and compression time is usually about 1 to 60 minutes, preferably about 10 to 30 minutes.

The tensile strength of the sheet obtained from the cationic microfibrillated plant fiber of the present invention is usually about 90 to 200 MPa, preferably about 120 to 200 MPa. The tensile strength of the sheet obtained from the cationic microfibrillated plant fiber of the present invention may vary depending on the basis weight or density of the sheet. In the present invention, a sheet having a basis weight of 100 g/m ² was produced, and the tensile strength of the sheet obtained from cationic microfibrillated plant fibers with a density of 0.8 to 1.0 g/cm ³ was measured.

In addition, the tensile strength is a value measured by the following method. The cationic microfibrillated plant fibers prepared and dried at a basis weight of 100 g/m ² were cut into rectangular sheets of 10 mm×50 mm to obtain test pieces. The test piece was installed in a tensile testing machine, and the stress and strain applied to the test piece were measured while applying a load. The load applied to the unit cross-sectional area of the test piece when the test piece was broken was defined as the tensile strength.

In addition, the tensile modulus of the sheet obtained from the cationic microfibrillated plant fiber of the present invention is usually about 6.0 to 8.0 GPa, preferably about 7.0 to 8.0 GPa. The tensile modulus of the sheet obtained from the cationic microfibrillated plant fiber of the present invention may vary depending on the basis weight or density of the sheet. In the present invention, a sheet having a basis weight of 100 g/m ² is produced, and the tensile modulus of the sheet obtained from cationic microfibrillated plant fibers having a density of 0.8 to 1.0 g/cm ³ is measured. In addition, the tensile strength is a value measured by the following method.

In addition, the cationic microfibrillated plant fiber of the present invention can be mixed with various resins to form a resin composite.

The type of resin is not particularly limited, for example, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, polyurethane resin, silicone resin, polyimide resin, Thermosetting resins such as resins, etc. Resin can be used individually by 1 type or in combination of 2 or more types. Preferred are phenolic resins; epoxy resins; unsaturated polyester resins.

The method of compounding the cationic microfibrillated plant fiber and the resin is not particularly limited, and a general method of compounding the cationic microfibrillated plant fiber and the resin can be employed. For example, there may be mentioned: a method in which a resin monomer liquid is sufficiently impregnated into a sheet or molded body made of cationic microfibrillated plant fibers, and then polymerized by heat, UV irradiation, or a polymerization initiator; A method for fully impregnating microfibrillated plant fibers into a polymer resin solution or resin powder dispersion and drying; fully dispersing cationic microfibrillated plant fibers in a resin monomer liquid and using heat, UV irradiation, and polymerization initiation A method of polymerizing it with an agent, etc.; a method of sufficiently dispersing cationic microfibrillated plant fibers in a polymer resin solution or a resin powder dispersion and drying them.

When compounding, surfactants, starches, polysaccharides such as alginic acid, natural proteins such as gelatin, animal glue, and casein, inorganic compounds such as tannins, zeolites, ceramics, and metal powders, colorants, and additives can also be added. Additives such as plasticizers, spices, pigments, flow regulators, leveling agents, conductive agents, antistatic agents, ultraviolet absorbers, ultraviolet dispersants, deodorants, etc.

The resin composite of the present invention can be produced as described above. Since the cationic microfibrillated plant fiber of the present invention has high strength, a high-strength resin composite can be obtained. This composite resin can be molded in the same way as other moldable resins, for example, it can be molded by heating and compression by mold molding. As for the molding conditions, the molding conditions of the resin may be appropriately adjusted as necessary.

Since the resin composite of the present invention has high mechanical strength, it can be used, for example, in fields requiring molded products of fibrous plant fibers and resin molded products containing microfibrillated plant fibers, and also for applications requiring more In the field of mechanical strength (tensile strength, etc.). For example, it can be used as inner packaging materials, outer packaging materials, structural materials, etc. of transportation machines such as automobiles, trams, ships, and airplanes; frames, structural materials, and internal components of electrified products such as personal computers, televisions, telephones, and watches; Housings, structural materials, internal parts, etc. of mobile communication devices such as mobile phones; housings, structural materials, internal parts, etc., of portable music reproduction machines, image reproduction machines, printing machines, copiers, sporting goods, etc.; building materials; stationery Efficient use of office machines, etc.

Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to them.

Example 1

Slurry of coniferous unbleached kraft pulp (NUKP) (aqueous suspension with a pulp concentration of 2% by weight) is passed through a single disc mill (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the refining process is repeated until the Canadian standard The freeness (CSF) value is below 100mL. The obtained slurry was dehydrated with a centrifugal dehydrator (manufactured by Kokusan Corporation) at 2000 rpm for 15 minutes, and the pulp concentration was concentrated to 25% by weight. Then, in the IKA mixer that the rotating speed is adjusted to 800rpm, add the above-mentioned pulp that is 60 weight parts by dry weight, the sodium hydroxide of 30 weight parts, the water of 2790 weight parts, after mixing and stirring at 30 ℃ for 30 minutes, the temperature is raised to At 80° C., 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) was added as a cationizing agent in an active ingredient equivalent of 375 parts by weight. After reacting for 1 hour, the reactant was taken out, neutralized, washed, and concentrated to obtain a cation-modified pulp with a concentration of 25% by weight. Table 1 shows the degree of substitution of cations in the cationically modified pulp.

In addition, the degree of substitution of cationic groups was obtained by measuring the nitrogen content (% by weight) of the sample by the elemental analysis method after measuring the lignin content (% by weight) in the sample by the Klason method, and calculating it by the following formula. The substitution degree mentioned here means the average number of moles of substituents per 1 mole of anhydroglucose unit.

Replacement degree of cationic group = (162×N)/{(1400-151.6×N)×(1-0.01×L)}

N: Nitrogen content (weight %)

L: lignin content (weight %)

The obtained cationically modified pulp was charged into a twin-screw kneader (KZW manufactured by Technovel Co., Ltd.), and subjected to defibration treatment. The defibrating conditions by the twin-screw kneader are as follows.

[Defibration condition]

Screw diameter: 15mm

Screw speed: 2000rpm (screw linear speed: 94.2m/min)

Defibering time: 150g of cationic modified pulp is defibrated under the treatment condition of 500g/hr～600g/hr. The time from feeding the raw materials to obtaining microfibrillated plant fibers was 15 minutes.

L/D: 45

Number of times for defibrillation treatment: 1 time (1 round)

Gate structures: 0.

Then, water was added to the cationic microfibril plant fiber slurry obtained by defibration to adjust the concentration of the cationically modified microfibril plant fiber to 0.33% by weight. The temperature of the slurry was set at 20°C. Then, 600 mL of the slurry was put into a tank, stirred with a stirring bar, and then pressure-reduced filtration was started immediately (5A filter paper manufactured by Advantec Toyo Co., Ltd. was used). The obtained wet web was heated and compressed at 110° C. and a pressure of 0.003 MPa for 10 minutes to obtain a cationic microfibrillated vegetable fiber sheet of 100 g/m ² . The tensile strength of the obtained sheet was measured. Table 1 shows the lignin content, the degree of substitution of cationic groups, and the values of various physical properties of the dried sheet. In addition, the measuring method of tensile strength is as mentioned above.

Example 2

Except for using softwood bleached kraft pulp (NBKP) as the pulp, and setting the addition amount of CTA to 180 parts by weight, and the addition amount of water to 2730 parts by weight, cationic modification was carried out in the same manner as in Example 1 to obtain Dry the sheet. Table 1 shows the lignin content, the degree of substitution of cationic groups, and the values of various physical properties of the dried sheet.

Example 3

Except having used glycidyltrimethylammonium chloride (GTA) as a cationization agent instead of CTA, it carried out cationic modification similarly to Example 2, and produced the dry sheet. Table 1 shows the lignin content, the degree of substitution of cationic groups, and the values of various physical properties of the dried sheet.

In addition, electron micrographs of the cationic microfibrillated plant fibers obtained in Example 3 are shown in FIGS. 1 and 2 . The fiber diameters of 100 arbitrary cationic microfibrillated plant fibers were actually measured from the 10,000-fold SEM image shown in FIG. 1 , and the number average fiber diameter was 87.02 nm. In addition, the fiber diameters of 50 arbitrary cationic microfibrillated plant fibers were actually measured from the 20,000-fold SEM image shown in FIG. 2 . As a result, the number average fiber diameter was 96.83 nm.

Example 4

Except that the sodium hydroxide was 7 parts by weight, the addition amount of GTA was 120 parts by weight, the addition amount of IPA was 2352 parts, and the addition amount of water was 588 parts, the same procedure as in Example 2 was carried out. Cationic modification to obtain cationic modified microfibrillated plant fibers with a substitution degree of cationic groups of 0.185.

In addition, an electron micrograph of the cationic microfibrillated plant fiber obtained in Example 4 is shown in FIG. 3 . The fiber diameters of 100 arbitrary cationic microfibrillated plant fibers were actually measured from the 50,000-fold SEM image shown in FIG. 3 . As a result, the number average fiber diameter was 57.79 nm.

Comparative example 1

Cationic modification was carried out in the same manner as in Example 3, except that the addition amount of CTA was 60 parts by weight and the addition amount of water was 2850 parts by weight during the cation modification, to obtain a dry sheet. Table 1 shows the lignin content, the degree of substitution of cationic groups, and the values of various physical properties of the dried sheet.

An electron micrograph of the cationic plant fiber obtained in Comparative Example 1 is shown in FIG. 4 . According to the 10000 times SEM image shown in Figure 4, the fiber diameters of 50 random cationic plant fibers were actually measured. As a result, the number average fiber diameter was 354.3nm, which is not the average value of the fiber diameter of 4 as in the present invention. ~~200nm cationic microfibrillated plant fibers.

Comparative example 2

A dry sheet was produced in the same manner as in Example 1 except that no cation modification was performed. Table 1 shows the lignin content and each physical property value of the dried sheet.

Comparative example 3

A cation-modified plant fiber was obtained in the same manner as in Example 3, except that no biaxial defibration treatment was performed after the cation modification. Table 1 shows the lignin content, the degree of substitution of cationic groups, and the values of various physical properties of the dried sheet.

Comparative example 4

Except for using commercially available powdered cellulose (KC flock W-100G, average particle size 37 μm, manufactured by Nippon Paper Chemicals Co., Ltd.), cationic modification was carried out in the same manner as in Example 3, and neutralization, dehydration, and drying were performed. . The dried product was pulverized with a hammer mill to obtain a cation-modified plant fiber having a cationic group substitution degree of 0.052 and an average particle diameter of 35 μm. An electron micrograph of Comparative Example 4 is shown in FIG. 4 . According to the 250-fold SEM image shown in Figure 4, the diameters of 50 random cationic plant fibers were actually measured. As a result, the average diameter of the cationic plant fibers was 13.31 μm, which is not the average value of the fiber diameters as in the invention of the present application. It is a cationic microfibrillated plant fiber of about 4 to 200 nm. Furthermore, Comparative Example 4 is an example in which the Example of Unexamined-Japanese-Patent No. 2002-226501 was reproduced.

[Table 1]

From the results of Comparative Example 3, it can be clearly seen that the strength and elastic modulus of the cationic modified plant fiber sheet obtained without biaxial defibration after GTA300% treatment are 79MPa5.5GPa, which is approximately the same as that of the untreated product. equal. According to the comparison of Example 3 and Comparative Examples 2 and 3, it can be confirmed that if only the pulp (NBKP) is subjected to GTA treatment, the tensile strength of the sheet will not be improved, but by performing biaxial defibration after GTA treatment, The tensile strength of the sheet is greatly improved.

Example 5

The aqueous suspension of cationic microfibrillated plant fibers prepared in Example 2 was filtered to obtain a wet web of cationic modified microfibrillated plant fibers. After immersing the wet web in an ethanol bath for 1 hour, it was heated and compressed at 110° C. and a pressure of 0.003 MPa for 10 minutes to obtain a bulky sheet of cationically modified microfibrillated plant fibers. In addition, the filter conditions were set to filter area: about 200 cm ² , degree of reduced pressure: -30 kPa, and filter paper: 5A manufactured by Advantec Toyo Co., Ltd.

Then, the bulky sheet of the obtained cationic microfibrillated plant fiber was cut into a width of 30 mm x length of 40 mm, dried at 105° C. for 1 hour, and the weight thereof was measured. Next, this sheet was impregnated with 100 parts by weight of unsaturated polyester resin ("SUNDHOMA FG283" manufactured by DH Material Co., Ltd.) and 1 part by weight of benzoyl peroxide ("NYPER FF" manufactured by NOF Corporation). in the resin solution. Impregnation was performed under reduced pressure (vacuum degree 0.01 MPa, time 30 minutes) to obtain an unsaturated polyester resin impregnated sheet. Then, with respect to this unsaturated polyester resin-impregnated sheet, several sheets of the same sheet were stacked so that the thickness of the molded body was about 1 mm. After discharging the excess resin, put it into a mold and perform hot stamping (temperature: 90°C, time: 30 minutes) to obtain a molded product of an unsaturated polyester composite of cationically modified microfibrillated plant fibers. Then, the weight of the obtained molded product was measured, and the fiber content (% by weight) was calculated from the difference with the dry weight of the sheet.

The length and width of the molded product were accurately measured with a vernier caliper (manufactured by Mitutoyo Corporation). The thickness of several places was measured with a micrometer (manufactured by Mitutoyo Corporation), and the volume of the molded product was calculated. In addition, the weight of the molded product was measured. Density was calculated from the obtained weight and volume.

A sample having a thickness of 1.2 mm, a width of 7 mm, and a length of 40 mm was prepared from the molded product, and the flexural modulus and flexural strength were measured at a deformation rate of 5 mm/min (load cell 5 kN). A universal testing machine Instron 3365 (manufactured by Instron Japan Company Limited) was used as a measuring machine. Table 2 shows the fiber content, flexural modulus, and flexural strength of the obtained resin composites.

Embodiment 6 and Comparative Examples 5-7

In addition to using the cationic microfibrillated plant fibers obtained in Example 3, the cationically modified pulp obtained in Comparative Examples 1 and 3, or the non-cationically modified microfibrillated plant fibers produced in Comparative Example 2, Except for the fibers, molded articles of Example 6 and Comparative Examples 5 to 7 were obtained by the same method as in Example 5. Table 2 shows the fiber content, flexural modulus, and flexural strength of the resin composites obtained in Example 6 and Comparative Examples 5 to 7.

[Table 2]

Embodiment 7 and Comparative Example 8

Dry sheets of the cationic microfibrillated plant fibers produced in Example 3 and the microfibrillated plant fibers produced in Comparative Example 2 were dried at 105° C. for 1 hour, and the weights were measured.

Then, these dried sheets were dipped (0.3 MPa) in a methanol solution (10% by weight) of a phenolic resin ("PHENOLITE IG-1002" manufactured by DIC Corporation), pre-dried at room temperature, and then dried at 50°C. It was dried under reduced pressure for 6 hours to obtain a dry sheet impregnated with phenolic resin, and the weight was measured. The fiber content (% by weight) was calculated from the difference in dry weight before and after resin impregnation.

Cut the obtained dry sheet impregnated with phenolic resin into a width of 30mm×length of 40mm, put several pieces of the same sheet into a mold, and heat stamping (temperature: 160°C, time: 30 minutes, stamping pressure: 100MPa) , and a composite molded product of cationic microfibrillated plant fibers and phenolic resin, and a composite molded product of non-cationized microfibrillated plant fibers and phenolic resin were respectively obtained.

The length and width of the molded product were accurately measured with a vernier caliper (manufactured by Mitutoyo Corporation). The thickness of several places was measured with a micrometer (manufactured by Mitutoyo Corporation), and the volume of the molded product was calculated. In addition, the weight of the molded product was measured. Density was calculated from the obtained weight and volume.

A sample with a thickness of about 1.6 mm, a width of 7 mm, and a length of 40 mm was made from the molded product, and the flexural modulus and flexural strength were measured at a deformation rate of 5 mm/min (load cell 5 kN). A universal testing machine Instron 3365 (manufactured by Instron Japan Company Limited) was used as a measuring machine. Table 3 shows the fiber content, flexural modulus, and flexural strength of the obtained resin composites.

[table 3]

Claims (7)

1. cationic microfibril string, it is the cationic microfibril string of 4～200nm for the mean value that carries out the fibre diameter after cation-modified with the compound that contains quaternary ammonium group.

2. a cationic microfibril string is characterized in that,

The degree of exchange of the quaternary ammonium group of each anhydrous grape sugar unit is more than 0.03 and less than 0.4, and the mean value of fibre diameter is 4～200nm.

3. the manufacturing approach of a cationic microfibril string, said cationic microfibril string is claim 1 or 2 described cationic microfibril strings, said method possesses following operation (1) and (2):

(1) hydroxyl in the material that contains cellulose fibre is reacted with the cationic agent with quaternary ammonium group, the material that will contain this cellulose fibre carries out cation-modified operation; And

(2) the cation-modified fiber of gained being separated fine mean value to fibre diameter in the presence of water is the operation of 4～200nm.

4. sheet material, it contains claim 1 or 2 described cationic microfibril strings.

5. heat-curing resin complex, it contains claim 1 or 2 described cationic microfibril strings.

6. heat-curing resin complex according to claim 5 is characterized in that,

Heat-curing resin is unsaturated polyester resin or phenolic resins.

7. the manufacturing approach of a heat-curing resin complex is characterized in that,

Possesses operation with claim 1 or 2 described cationic microfibril strings and heat-curing resin mixing.

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